Method of making picker sticks for use in shuttle looms



Feb. 6, 1962 .1. v FERRAN 3,020,187

METHOD OF MAKING PICKER s IcKs FOR USE IN SHUTTLE LOOMS FiledMay 13, 1957 INVENTOR JUAN V/LA FER/PAN M/ggg 3,62%,137 Patented Feb. 6, 1962 3,020,187 METHOD OF MAKING PICKER STICKS FUR USE IN SHUTTLE LOGMS Juan Vila Ferrari, 82 Arnilcar St., Barcelona, Spain Filed May 13, 1957, Ser. No. 658,606 Claims priority, application Spain Oct. 10, 1952 2 Claims. (Cl. 156-250) ments with a view of securing a resulting product that would withstand the hard use to which it is subjected in loom performance.

The picker stick has been'manufactured with diverse materials. In one particular arrangement, slabs or sheets are subjected to compression in order to obtain a greater hardness'in the wood utilized. Likewise, attempts have been made to avoid deformation or bending of the picker stick once manufactured, but no definitive results have been achieved in any of the attempts made hitherto.

With the improved method of manufacture constituting this invention, the desired objects have been attained.

As a characteristic feature of the procedure, sheets or slabs are subjected to a preliminary treatment to eliminate their defects and natural rigidity and at the same time to increase their resistance to wear. The tendency to deformation or bending is thereby removed. By subjecting the slabs at the end of the procedure to a hardening or rigidifying treatment the picker stick acquires a suitable enduring shape.

The procedure comprises a chemical treatment to render the wood sheets or slabs moldable or formable, which treatment may be completed on the said sheets or slabs or, alternatively, started in the raw material and thereafter completed and accelerated during the gluing process of a stack consisting of suitable slabs to form the wedge constituting the picker stick.

The procedure to be followed will depend on whether the wood is dry or green. When the wood is dry or seasoned, consideration must be given to the capacity of the wood to absorb gaseous ammonia under certain conditions. When the sheets or slabs are subjected to a temperature increase and then allowed to cool down in an ammonia atmosphere, these sheets or slabs absorb gas in a volumetric ratio of 90 to 1 based on the wood volume. In this case the treatment is completed and the resulting wood is rigid yet thoroughly moldable when hot.

The treatment may be performed in a preliminary step, bysubjecting the slabs or sheets to impregnation in an ammonia containing bath with the slabs piled up, as hereinafter'disclosed, so that in the gluing step the desired moldability can be completed by taking advantage of the heat in the gluing step.

The sheets or slabs are piled up by arranging them according to a stair-step arrangement, the length and number of these slabs depending on the final angle of the desired taper. jected to treatment similar to the sheets are placed on each step, said pieces having a thickness approximately half of the height of the step. These pieces fill the spaces and give greater continuity to the slope when suitable pressure is applied thereon.

When assembling slabs or sheets they may be coated between plies with the usual synthetic resin adhesive which sets upon final application of heat and pressure. The pressure to which the stack is subjected, together with a suitable temperature for the gluing treatment, has the effect of increasing the moldability hereinbefore referred to. Due to this condition, the deformation of the wood by compresison is very even and the resulting tapered pile of slabs is a moldable block suitable to be shaped before being subjected to the rigidifying treatment which is the last step in the procedure.

When the wood is green, urea is used. The water in the wood reacts with the urea to produce ammonium carbonate according to the reaction O NH4 a v oNH, with the result that the wood becomes moldable in the same manner as explained in the case'of dry wood.

The result is to provide thepicker stick or the assemblage from which the same is to be obtained through successive cuts, with a plasticity permitting bending in any direction, preferably while hot. The material thenis adapted for bending, straightening and compressing as desired, for obtaining a correct shape which afterwards is made enduring by a suitable treatment to obtain perma nent rigidity.

The treatment providing the pressed and glued product with enduring rigidity consists in subjecting the block to a slight impregnation wtih neutral aluminum acetate Al(CH .CO.O) which produces, when diluted in water, aluminum hydroxide Al(OH) which is afterwards converted by heating to aluminum oxide A1 0 the reaction being carried through within an oven or suitable reservoir.-

Pieces of wood which have been sub- To save fuel, this rigidifying treatment may be car-' ried out simultaneously with that of pressing and gluing which uses heat in any case.

Urea treated green woods may, advantageously, undergo a treatment to obtain the enduring rigidity by utilizing a Formol bath in the presence of an alkali or an acid, said treatment giving the same result as that previously re ferred to in which acetate is utilized.

The formable or moldable procedure which the wood'is subjected to eliminates defects and natural rigidity.

In making the product from which the sticks are cut I form a stack of slabs by taking sheets or slabs about 2 mm. thick and whose lengths are dependent on the angle of the taper it is desired to obtain, and place wood pieces about 1 mm. thick on the steps, with the fibres disposed transversely to the wedge length.

Referring to the drawing:

FIG. 1 shows in detail the stack of sheets or slabs with pieces inserted transversely on the steps; and

FIG. 2 shows the same stack after it has been finally processed and ready for cutting into sticks.

The sheets or slabs 1, of even thickness and having lengths adapted to the taper angle 2 which it is desired to obtain, are formed in a pile. Transverse pieces 4 are placed on the steps 3, which pieces are as thick as half 1e height of the step. The confining slabs 5 and 6 are placed to cover the steps and the filler pieces prior to compression of the pile. The wedge angle formed due tothe compression is shown in FIG. 2,.wherein the stack is wholly included between two slabs 5 and 6, the whole forming thetaper of the picker stick.

By cutting transversely a stack, as shown in FIG. 2, a given number of picker sticks can be produced.

The following are examples of various procedures that may be followed in carrying out my invention:

(1) T rcatment of seasoned wood with ammonia gas. The wood slabs are placed in a closed oven and heated to a temperature depending on several factors, such as the kind and condition of the wood to be treated, or even the degree of seasoning. For example, a temperature of 60 C. applied during a period of 30 minutes n most cases provides for an even heat distribution and impregnation of the most internal spaces of the wood pieces. The heating is thereafter discontinued and the material is allowed to cool down in the same oven. while feeding therein further ammonia gas at atmospheric pressure until the slabs or sheets reach room temperature. The duration of this treatment is defined in terms of the amount of absorbed gas in the wood, and it is assumed to be completed when ammonia has been absorbed in a volumetric ratio of 90 to 1 based on the wood volume.

(2) Treatment of seasoned wood with aqueous ammonia.The wood pieces are immersed in a 20% ammonia aqueous solution at room temperature for 15 minutes. After this period the wood is withdrawn from the bath and allowed to' dry either by natural drying by outdoors piling or by speeded drying by any known method such as a continuous tunnel dryer. The so treated material has reached a partial moldability which can be completed by the heat present in the molding or forming stage instead of using additional heat in the heating and further cooling the wood in ammonia atmosphere for the absorption of ammonia gas.

(3) Treatment of green or unseasoned wd.- Green wood is not treated with ammonia, neither gas nor aqueous. The treatment of wood in this case is effected with an ammonia-releasing chemical such as urea. In an em= bodiment of this method, the wood, in the same form as in the previous treatments, is immersed in a water bath containing 5% by weight of urea referred to the 'weight of water}. This treatment is etfected for a period of time, depending on several factors, but a period of to minutes has been suflrcient for most practical applieations of the process and most conditions of the wood The most suitable treatment time can be determined, for example, by a measure of the urea absorption, that is, the loss in u'r'ea contents of the bath as regards the weight of wood; The temperature of this bath is about 50 C.

When the wood contains a great percentage of water,- such as in the ease of wood used immediately after the cutting thereof, the water bath may be dispensed with and the function thereof charged to the moisture contents of the wood. In this case the wood pieces are piled closely and layers of urea powder are spread between successive wood layers. The amount of urea introduced in the wood by absorption can be determined by previously weighing the urea to be absorbed and conducting the absorption until this is complete; or otherwise by measuring the urea contents in samples periodically withdrawn from the pile. This operation can be effected indoors at room temperature or outdoors provided that an excessive evaporation of the wood moisture does not take place with, of course, would reduce the absorption ability of the wood.

I The wood is dried at low temperature (after any of the above treatments), room or slightly increased room temperature, until the moisture content is reduced to a maximum of 5-20%.

(4) Gluing step.This can be effected by means of any usual glue or adhesive commonly utilized in the handling of wood, for example, a phenolic or urea resin based glue. The adhesive is applied by spreading or smearing, according to the'nature thereof, on the faces of the wood pieces'to be contacted together. The application of the glue can be effected either on one or both contacting faces. The sheets are then piled up between the two plates of a press. In both cases the pressure to be applied is about 60-70 kg. cm. As to the temperature, when using a phenolic resin based glue a heating of up to 160 C. is suitable, while in the case of an urea of electrical heaters or steam coils placed behind the plates. Many types of such presses are already known in the art.

(5) Urea hardening pr0cess.This applies only for urea treated woods, that is, green of unseasoned woods which have been treated'with urea, either in powder or liquid form. The urea treated wood is immersed in an aqueous concentrated Formol bath to which a small amount of an alkali or acidic catalyzer has been added. As alkali catalyzer, sodium or potassium hydroxide can be used. Acidic catalyzers are strong acids such as bydrochloric and sulfuric acids.

Here, presumably, a condensation-polymerization reaction takes place between urea and formaldehyde, and this reaction is conducted so that a desired degree of hardness is obtained in the end product, this result being dependent on temperature and time conditions.

The following shows a typical example of operation with a urea treatment: The starting material is beech-tree wood and is treated just after felling the tree, i.e., with its whole moisture contents. The wood is cut into laminations which are sprayed with urea in powdered form and further layers of wood and urea powder are added forming a stack. The operation is watched. and further amounts of urea are added in the manner described so that there is always an excess of this substance throughout the course of the absorption.

In this case the absorption of urea occurs simultaneously with the drying of the material, thereby saving time. Absorption and drying can be effected independently as described above and the operation is continued until the wood shows a content of 10% moisture.

The laminations are removed from the pile and cleaned of the excess urea powder. The faces of the laminations are coated with a commercial urea-formol resin based glue (50% urea+50% formol), which is applied with a brush or spraying gun. The so coated laminations are glue the temperature can be lowered to 130 C. The 7 operation can be effected in any of the so-called plate presses used in wood works which are adapted to supply heat to the material being pressed; for example, by means piled up on the lower plate of an electrically heated plate press forming a stack of the thickness required for the picker sticks to be formed. During this piling insertions are made as heretoforeexplained. 7

Then a pressure of 150 kg. cm? is applied in the press whiel the plates are heated at C. The comparatively thin stack allows the temperature to reach all the .mass'of wood in a short period. The pressure in this instance can be varied according to the degree of volume reduction and toughness desired. The time of treatment is 45 minutes. This operation, of course, is performed with the press plates formed according to the final shape desired. After the above period has elapsed, heating is discontinued and the press allowed to cool naturally or with the aid of a circulation of cold Water.

If the laminations are wide enough the wood can be cut longitudinally to produce several sticks which are thereafter immersed in a concentrated aqueous solution of formol to which are added some drops of sulfuric acid. The temperature is controlled as regards time so that a slight polymerization is obtained. This prevents the sticks from becoming too brittle.

The heat generated during performance thereof in the loom continues the polymerization process, thereby giving a further wear resistance and further improving the properties of the stick.

The following is an example of hardening with aluminum acetate:

The ammonia treated wood is immersed in an aqueous solution containing lO-l5% aluminum acetate. This treatment is effected at 25-50 C., and to this end the same residual heat of the forming or pressing process can be used. Thereafter the wood may be heated to convert aluminum acetate into aluminum oxide; or this heating may be effected due to the working of the pick in the loom as defined above.

It is thus seen that according to the invention the need for symmetrically coupling sheets or profiles as hitherto made is avoided, as well as the work of cutting profiles from different sections of the trunk and blending the sections to compensate deformations. The method also facilitates the work of piling up and gluing, thereby allowing the manufacture of suitable straight and rigid picker arms which give good efficiency during their working.

Various modifications, such as shape and size, as well as suitable materials can be utilized in the present invention without departing from the scope thereof as defined in the appended claims.

I claim:

1. The method of forming picker sticks for looms, comprising treating a plurality of thin slabs of green wood lumber with powdered urea, drying the slabs to approximately 10% moisture content, assembling the slabs into a Wedge shaped stair step pile, laminating said slabs with urea-formaldehyde resin adhesive, placing filler pieces of less thickness in the steps, positioning a confining slab of wood lumber to cover the steps and the filler pieces, thereafter subjecting the assemblage to heat and compression to both mold the pile and compress the adhesive, then treating the compressed pile with a concentrated solution of formaldehyde, then cutting the pile transversely to produce a plurality of wedge shaped stick units.

2. The method of claim 1 wherein the compression to which the assemblage is subjected is 150 kg. cm. and the temperature is 125 C.

References Cited in the file of this patent UNITED STATES PATENTS 1,680,529 Richter et al. Aug. 14, 1928 2,112,245 Luckhaupt Mar. 29, 1938 2,147,904 Kukula Feb. 21, 1939 2,298,017 Loughborough Oct. 6, 1942 2,313,953 Loughborough Mar. 16, 1943 2,589,316 Young Mar. 18, 1952 2,664,835 Sorensen Jan. 5, 1954 FOREIGN PATENTS 133,088 Great Britain Oct. 9, 1919 OTHER REFERENCES Waterproofing and Hardening Paper by Means of Aluminum Acetate, Lambrette, Paper Trade Journal, August 4, 1927, pages 57-58. 

1. THE METHOD OF RORMING PICKER STICKS FOR LOOMS, COM PRISING TREATING A PLURALITY OF THIN SLABS OF GREEN WOOD LUMBER WITH POWDERED UREA, DRYING THE SLABS TO APPROXIMATELY 10% MOISTURE CONTENT, ASSEMBLING THE SLABS INTO A WEDGE SHAPED STAIR STEP PILE, LAMINATING SAID SLABS WITH UREA-FORMALDEHYDE RESIN ADHESIVE, PLACING FILLER PIECES OF LESS THICKNESS IN THE STEPS, POSITIONING A CONFINING SLAB OF WOOD LUMBE TO COVER THE STEPS AND THE FILLER PIECES, THEREAFTE RSUBJECTING THE ASSEMBLAGE TO HEAT AND COMPRESSION TO BOTH MOLD THE PILE AND COMPRESS THE ADHESIVE, THEN TREATING THE COMPRESSED PILE WITH A CONCENTRATED SOULATION OF FORMALDEHYDE, THEN CUTTING THE PILE TRANSVERSELY TO PRODUCE A PLURALITY OF WEDGE SHAPED STICK UNITS. 